Numerous technologies for the preparation of xanthohumol are known in the art. The application DE 199 39 350 A1 describes a process for the preparation of a xanthohumol-enriched hop extract, wherein mixtures of water and ethanol were used for extraction. The obtained extract contained 5 to 15% of xanthohumol.
The patent EP 1 424 385 B1 discloses a method of extracting xanthohumol from the raw xanthohumol-containing material by use of compressed CO2 as a solvent under a pressure above 500 bar and at temperatures above 60° C.
The application CN 101440029 discloses a method of extracting xanthohumol from the hop plant and xanthohumol-containing products, wherein the extraction with an organic solvent assisted by ultrasounds is conducted, followed by mixing with diatomite, filtering, washing out with water/methanol mixture, concentrating, precipitating and drying to obtain xanthohumol of the 86% purity.
The patent EP 2 187 899 B1 discloses a process for the preparation of a composition of the high xanthohumol content from a hop plant, wherein a salt is added to a xanthohumol-containing solution to the concentration in the range of from 0.05 to 5.0M, followed by increasing pH to from 10.5 to 12.0, filtering the obtained precipitate, acidifying the filtrate to pH 7-8 to obtain the xanthohumol precipitate of the 40-95% purity.
The patent application U.S. Ser. No. 11/790,365 discloses a process for the preparation of the powder of the high (60-90%) xanthohumol content, comprising suspending a xanthohumol-enriched extract in an alkaline solution, separating insoluble products, neutralizing and precipitating the dissolved xanthohumol with an acid and isolating the product.
Patent CN 101433592 discloses use of various adsorption resins to prepare high purity xanthohumol.
In conclusion, analysis of the prior art discloses unequivocally that there is a need for developing a simple and inexpensive process for the preparation of high purity xanthohumol.